我想知道是否可以在 libxml2 中使用相对 XPath 表达式。
这来自 javax.xml.xpath API，我想使用 libxml2 做类似的事情：
Node widgetNode = (Node) xpath.evaluate(expression, document, XPathConstants.NODE);
通过对元素的引用，现在可以编写相对 XPath 表达式来选择子元素：
XPath xpath = XPathFactory.newInstance().newXPath();
String expression = "manufacturer";
Node manufacturerNode = (Node) xpath.evaluate(expression, **widgetNode**, XPathConstants.NODE);
这是一些代码示例：
xmlXPathContextPtr xpathCtx = xmlXPathNewContext(doc);
const xmlChar* xpathExpr = BAD_CAST "//column";
xmlXPathObjectPtr columnXPathObj = xmlXPathEvalExpression(xpathExpr, xpathCtx);
// Do whatever you want with your query here. Usually iterate over the result.
// Inside this iteration I do:
cur = columnNodes->nodeTab[i];
// Important part
xpathCtx->node = cur;
// After which you can do something like:
xmlXPathObjectPtr screenXPathObj = xmlXPathEvalExpression(BAD_CAST "screen", xpathCtx);
xmlNodeSetPtr screenNodes = screenXPathObj->nodesetval;
for (int j = 0; j < screenNodes->nodeNr; j++) {
// You're now iterating over the <screen>s inside the curent <column>
}
希望这可以帮助某人。
设置 xmlXPathContext 对象的节点成员。